Voltage requirements for R&R wtc pumps and brushless motor

[Timothy L]

1) What voltage should be applied to the standard pumps and the brushless motor provided with the R&R wtc’s please?

2) what size / type fuse should be used; where should it be located and why?

Thank you.

[Subculture]

1) What voltage should be applied to the standard pumps and the brushless motor provided with the R&R wtc’s please?

The pumps are rated for 12 volt operation, but you can operate them on less voltage just fine they just pump a little slower. I wouldn’t want to run them on anything greatly over 12 volts though, as it will stress the motor.

Brushless motors will operate over a very wide voltage range, it’s mainly the load you put on them that determines the best choice. This depends on prop diameter and pitch, plus the speed you’re after alongside the diameter of the motor can and its RPM per volt usually given as KV. Most brushless motors don’t come with a rating for marine props, however most do come with a recommendation for aeroplane propeller sizes. I find a pretty simple rule of thumb if you’re less experienced at selecting motors for props is to take the median air prop size for that motor and divide it by five for a marine equivalent. E.g. a motor designed to swing a 10” diameter aeroplane prop will likely work well for a 2” diameter boat prop.

2) what size / type fuse should be used; where should it be located and why?

At a minimum you want a fuse fitted just after the battery pack, that way any short circuit condition in your electronics should be protected against. I would rate this at least 50% above your maximum continuous current load. For most models a 15A fuse is usually adequate, fit a slow blow. Larger or high speed models may need a higher rating. Some don’t like fitting fuses, but you should bear in mind that without one, your wiring and/or electronics then become the ‘fuse’. A short circuit condition with high capacity batteries can produce enough heat to melt through your cylinder, especially so with lithium batteries which can supply a lot of current.

if you want to get a bit more fancy you could fuse each individual circuit, e.g, pump, drive motor, radio/bec which gives you some diversity should one item fail. This comes at the expense of additional wiring and fuses. A single fuse on the power line is simple and should protect the boat from a bad short condition, but it will kill all power, which leaves you dead in the water.

[Timothy L]

Subculture -
Thank you so much for such a well stated and detailed answer. It is most helpful!

(Taking your input in mind it looks like a 11.1v 5-6000mA lipo will work fine.)

[Subculture]

That’ll work. An alternative is a 4s LiFe pack giving 12.8v